On 2012-10-22 21:50, Hugo Mills wrote: >>>>> It's more like a balance which moves everything that has >>>>> some (part of its) existence on a device. So when you have >>>>> RAID-0 or RAID-1 data, all of the related chunks on other >>>>> disks get moved too (so in RAID-1, it's the mirror chunk as >>>>> well as the chunk on the removed disk that gets >>>>> rewritten). >>> >>> Does this mean "device delete" depends on an ability to make >>> writes to the device being removed? I immediately think of SSD >>> failures, which seem to fail writing, while still being able to >>> reliably read. Would that behavior inhibit the ability to >>> remove the device from the volume? > No, the device being removed isn't modified at all. (Which causes > its own set of weird problemettes, but I think most of those have > gone away).
IIRC, when a device is deleted, the 1st superblock is zeroed. Moreover btrfs needs to be able to read the device in order to delete it. Of course these rules aren't applied when a device is classified as "missing". See the function btrfs_rm_device() in fs/btrfs/volumes.c for the details. > -- gpg @keyserver.linux.it: Goffredo Baroncelli (kreijackATinwind.it> Key fingerprint BBF5 1610 0B64 DAC6 5F7D 17B2 0EDA 9B37 8B82 E0B5 -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
